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Numerous studies have shown that pregnancy outcomes can be reduced with improved glycemic control. In particular, pre-pregnancy care has been shown to assist women improve glucose control during the crucial period of organogenesis, and is associated with reduced rates of adverse pregnancy outcome including major congenital malformation, stillbirth and neonatal death.

Technological advances aimed at reducing glycemic excursions and improving glucose control in patients with diabetes include the continuous glucose monitoring (CGM) system. We hypothesize that real-time CGM will assist women with type 1 diabetes to improve their glycemic control before and during pregnancy.

Glycemic Control in pre-pregnant group [ Time Frame: 24 weeks or at conception ]

Glycemic control as measured by HbA1c at 24 weeks or at conception. If the patient becomes pregnant, than a HbA1c will be measured post-confirmation of a positive pregnancy test and will contribute to the primary outcome.

Glycemic Control in pregnant group [ Time Frame: 34 weeks gestation ]

Glycemic control as measured by HbA1c at 34 weeks gestation. In women who do not progress to 34 weeks gestation, the latest measured HbA1c will be used to contribute to the primary outcome.

Secondary Outcome Measures :

Time in target in pre-pregnant group [ Time Frame: 12 and 24 weeks after randomization ]

Time in target at 12 and 24 weeks after randomization

HbA1c and time in target, in pre-pregnant group who became pregnant within 24 weeks from randomization [ Time Frame: 24 weeks and 34 weeks gestation ]

HbA1c and Time in target at post-confirmation of a positive pregnancy test, 24 weeks and 34 weeks gestation for those who start pre-pregnant and become pregnant

Time in target in pregnant group [ Time Frame: Randomization, 24 weeks and 34 weeks gestation ]

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Ages Eligible for Study:

18 Years to 40 Years (Adult)

Sexes Eligible for Study:

Female

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

Clinical diagnosis of type 1 diabetes and using daily insulin therapy for at least one year

Age 18-40 years

Insulin regimen involves either the use of an insulin pump or multiple daily injections of insulin (at least 3 shots per day). Subjects using premixed fixed doses of insulin at the time of enrolment will not be eligible. Insulin regimen must be stable for at least 4 weeks (i.e. on multiple insulin injections or on insulin pump) prior to randomization.

No expectation that subject will be moving out of the area of the clinical center during the next year, unless the move will be to an area served by another study center

Informed Consent Form signed by the subject

In addition, specific eligibility criteria apply to the respective groups:

Pre-pregnancy Group:

Patients who are planning pregnancy and wish to optimise glycemic control before conception

Pregnancy Group:

Pregnancy gestation ≤13 weeks, 6 days at time of randomization

Live singleton fetus

Dating ultrasound (US) done to confirm gestational age, viability and rule out multiples. Gestational age will be based on the last menstrual period (LMP) provided there is a ≤5 day discrepancy with US dates in the first trimester and ≤10 day discrepancy with US dates in the second trimester. If the dates from LMP are outside these limits, the US dates will be used as the best estimate of gestational age.

Exclusion Criteria:

Type 2 diabetes

Gestational diabetes

Previous participation in the study

Estimated GFR <60 ml/min/1.73

The presence of a significant medical disorder or use of a medication such as oral glucocorticoids that in the judgment of the investigator will affect the wearing of the sensors or the completion of any aspect of the protocol.

If the investigator is uncertain whether the patient would be eligible; i.e. if the medical disorder would constitute an exclusion, the Steering Committee will be asked to make the decision.

Inpatient psychiatric treatment in the past 6 months

Subjects using premixed fixed doses of insulin at the time of enrolment

In addition, specific exclusion criteria apply to the respective groups:

Pre-pregnancy Group:

HbA1c <7.0% or >10.0%

Pregnancy Group:

HbA1c <6.5% or >10.0%

Known current higher order pregnancies (twins, triplets, etc.) These women will be excluded as they have a higher rate of adverse outcomes and could lead to inequalities if they are unequally distributed between the groups.